Paul, far be it from me to criticise what is obviously an outstanding model which you have put in many hours, so I offer the following as information only (with which to improve your masters for full-on resin production!
)
The Portee cab has a pronounced false floor which raises the intercept line of the floor and front guards (Wings, fenders?) higher than an ordinary 12 cab (such as the Tamiya GT). The protective "flaps" to provide shelter with the widened cab are also quite rounded.